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We have done a few Suzuki DRZ400SM's and thought it was time to share! The SM differs from the dirt DRZ in that it runs 47mm Showa twin chamber forks. Unfortunately they are not the current specification the MX bikes use, but still very good for the SM. The forks run the "old" 23mm cartridge while the shock is very similar to the dirt DRZ's 50mm Showa unit. Springs are a bit light for most riders, our Intercomp spring tester recorded 0.46kg/mm for the fork springs and 5.3kg/mm for the rear. While this is heavier than the dirt model in the forks, the internal specifications of the SM are still very dirt orientated. |
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We also ran the shock and fork in the dyno and got the results we expected, soft valving. So we fitted our T-Valve kits front and rear with a corresponding increase in dampening force (see graph below). All over the result is much reduced brake dive, easier turn entry, less squat on turn exit and a more stable ride. |
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Goldwings represent many things to many riders but most agree the forks are a bit of a let down for an otherwise cool bike. We installed one of our fork kits to an 1988 GL1500 this week and thought you might be interested in what's under all that plastic. |
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The 41mm Showa forks are common to Goldwings from 88-94. They are a damper rod design with a brake actuated anti dive system to increase compression dampening when the calipers are under load. The springs are an unusual dual spring set-up that end up with a very low average spring rate of 0.39kg/mm. Yes you read that right, it's 125cc MX territory in the spring department. To hold the beastie up Honda use a mere 120mm of spring preload. This makes for a bit of excitement when you remove the fork caps. This explains why the forks are able to be bottomed and topped (!) out while sitting on the bike. We use springs in the 0.80kg/mm to 1.00kg/mm range as replacements along with less pre-load to keep the static sag in the ballpark. To give the fork some much needed compression dampening we fit a set of our V4s valves, designed for damper rod forks, along with heavier actuating springs suited to the Goldwing. There are also some changes we make to the rebound circuit of the forks for the heavier springs along with mods to the anti dive on compression. |
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